Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K6/00—Preparations for dentistry
  • A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
  • A61K6/831—Preparations for artificial teeth, for filling teeth or for capping teeth comprising non-metallic elements or compounds thereof, e.g. carbon
  • A61K6/838—Phosphorus compounds, e.g. apatite
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K6/00—Preparations for dentistry
  • A61K6/70—Preparations for dentistry comprising inorganic additives
  • A61K6/71—Fillers
  • A61K6/77—Glass
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K6/00—Preparations for dentistry
  • A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
  • A61K6/802—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/40—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material
  • A61L27/42—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material having an inorganic matrix
  • A61L27/425—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material having an inorganic matrix of phosphorus containing material, e.g. apatite
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  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/50—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
  • A61L27/54—Biologically active materials, e.g. therapeutic substances
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/50—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
  • A61L27/56—Porous materials, e.g. foams or sponges
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/097—Glass compositions containing silica with 40% to 90% silica, by weight containing phosphorus, niobium or tantalum
• • C—CHEMISTRY; METALLURGY
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  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/11—Glass compositions containing silica with 40% to 90% silica, by weight containing halogen or nitrogen
  • C03C3/112—Glass compositions containing silica with 40% to 90% silica, by weight containing halogen or nitrogen containing fluorine
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  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C4/00—Compositions for glass with special properties
  • C03C4/0007—Compositions for glass with special properties for biologically-compatible glass
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  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/447—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on phosphates, e.g. hydroxyapatite
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  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
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  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
  • C04B35/6303—Inorganic additives
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  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
  • C04B35/632—Organic additives
  • C04B35/634—Polymers
  • C04B35/63404—Polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • C04B35/63424—Polyacrylates; Polymethacrylates
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  • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
  • C04B38/06—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by burning-out added substances by burning natural expanding materials or by sublimating or melting out added substances
  • C04B38/0615—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by burning-out added substances by burning natural expanding materials or by sublimating or melting out added substances the burned-out substance being a monolitic element having approximately the same dimensions as the final article, e.g. a porous polyurethane sheet or a prepreg obtained by bonding together resin particles
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2300/00—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices
  • A61L2300/40—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices characterised by a specific therapeutic activity or mode of action
  • A61L2300/412—Tissue-regenerating or healing or proliferative agents
  • A61L2300/414—Growth factors
• • A—HUMAN NECESSITIES
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  • A61L2400/00—Materials characterised by their function or physical properties
  • A61L2400/08—Methods for forming porous structures using a negative form which is filled and then removed by pyrolysis or dissolution
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2430/00—Materials or treatment for tissue regeneration
  • A61L2430/02—Materials or treatment for tissue regeneration for reconstruction of bones; weight-bearing implants
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  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
  • C04B2111/00836—Uses not provided for elsewhere in C04B2111/00 for medical or dental applications
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  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
  • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
  • C04B2235/3201—Alkali metal oxides or oxide-forming salts thereof
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  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
  • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
  • C04B2235/3205—Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
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  • C04B2235/34—Non-metal oxides, non-metal mixed oxides, or salts thereof that form the non-metal oxides upon heating, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
  • C04B2235/3418—Silicon oxide, silicic acids or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint
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  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
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  • C04B2235/44—Metal salt constituents or additives chosen for the nature of the anions, e.g. hydrides or acetylacetonate
  • C04B2235/444—Halide containing anions, e.g. bromide, iodate, chlorite
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  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
  • C04B2235/44—Metal salt constituents or additives chosen for the nature of the anions, e.g. hydrides or acetylacetonate
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  • C04B2235/74—Physical characteristics
  • C04B2235/77—Density

Definitions

• the present invention relates to a method for producing a ceramic foam material and, in particular, a glass-reinforced ceramic foam material for use in biomedical applications and comprising hydroxyapatite and a biocompatible glass.
• the apatite group of minerals are based on calcium phosphate, with stoichiometric hydroxyapatite having a molar ratio of Ca/P of 1.67.
• Hydroxyapatite has the chemical formula Ca 10 (P0 4 ) 6 (OH) 2 .
• Porous bio-ceramic materials may provide secure fixation of an implant as a result of bony ingrowth and mechanical interlock.
• Hydroxyapatite has potential for hard tissue replacement and/or augmentation and there are a number of porous hydroxyapatite based implant materials currently available on the commercial market. Many of these materials are derived from either animal cahcellous bone or coral, which is hydrothermally treated so as to convert the natural ceramic component into hydroxyapatite, while preserving the natural porous structure. For example, Endobon (RTM) is produced via the hydrothermal conversion of bovine cancellous bone.
• RTM Endobon
• a second method utilises the natural structure of coral which by a hydrothermal processing method converts the calcium carbonate based coral to hydroxyapatite, while retaining the porous structure of the coral.
• naturally-derived materials may contain heavy metals which have been incorporated into the structure.
• the materials are therefore susceptible to variability in their structure and hence the tissue reaction on implantation is variable.
• Porous hydroxyapatite produced using synthetic hydroxyapatite while offering a more controllable material in terms of both chemistry and morphology, has low bioactivity. Substitutions may be made into the structure, but these make the material unstable at high temperatures and thus difficult to process without loss of beneficial ions (such as C0 3 2- ) or decomposition.
• Ceramic foams are conventionally formed by infiltrating a polymer foam with a slip, which is a fine slurry of ceramic particles in a fluid, such as water. When the aggregate is fired, the slip bonds to the polymer foam to give an image of the original foam, which is burnt off. Ceramic foams may also be made by chemical vapour deposition on to a substrate of reticulated carbon foam.
• the present invention aims to provide a method for the manufacture of porous materials with improved properties which are suitable for use in medical applications.
• the present invention provides a method for the production of a glass-reinforced ceramic foam material for use in biomedical applications and comprising hydroxyapatite and a biocompatible glass, which method comprises: (a) providing a foam carrier;
• a slip comprising a liquid carrier and either (i) a biocompatible glass particulate and a ceramic particulate selected from one or both of hydroxyapatite and apatite or (ii) a composite ceramic-glass particulate comprising a biocompatible glass with one or both of apatite and hydroxyapatite;
• Foams are three-dimensional cellular solids and may be classified as either open-celled or closed- cell.
• the relative density of a cellular material is defined as the ratio of the density of the cellular material to that of the solid material.
• the relative density generally falls within the range of from 0.05 to 0.7, i.e. 30 to 95 % porous.
• determination of the relative density of a porous structure can give an indication of the degree of pore connectivity within the structure.
• a structure with a relative density of less than approximately 0.2 i.e. 80 % porous
• one with a relative density of more than approximately 0.2 i.e. 80% porous
• open interconnected porosity is of primary interest.
• biocompatible glass as used herein is meant that the glass is substantially free of any metal ions which are not tolerated by the body (except for Al 34" , provided that ' the amount is small) .
• the slip advantageously further comprises a deflocculant to enable the particles in the slip to remain in suspension for extended periods of time.
• Suitable deflocculants include anionic deflocculants, for example one or more of sodium carbonate, sodium oxalate, sodium phosphate, sodium hydroxide, sodium silicate, sodium hexametaphosphate and sodium polyacrylate.
• anionic deflocculants for example one or more of sodium carbonate, sodium oxalate, sodium phosphate, sodium hydroxide, sodium silicate, sodium hexametaphosphate and sodium polyacrylate.
• a particularly preferred deflocculant is commercially available under the name Dispex N40.
• the choice of a suitable deflocculant may be made on the basis of the surface charge of the slip.
• Surface charge may be determined by conventional means, for example by zeta potential measurements.
• the rheology of the slip may also be assessed to optimise the deflocculant concentration and also the solids concentration in suspension.
• the slip may further comprise one or both of a surfactant and a dispersant.
• the slip preferably has a pH in the range of from 7 to 11, preferably from 8 to 10, more preferably from 8.5 to 9.5.
• the slip preferably has a viscosity ⁇ 30 Cps, more preferably ⁇ 25 Cps, still more preferably from 5 to 20 Cps. Viscosity may be measured using a cone and plate visco eter.
• the slip should have a viscosity to enable it to substantially coat the foam carrier uniformly.
• the viscosity and rheological properties of the slip may be adjusted by altering the relative amounts of the liquid carrier and the ceramic and glass particulates.
• the viscosity may also be adjusted by the addition of a deflocculant.
• the solids concentration in the slip is preferably adjusted to ensure that the ceramic/glass foam has a substantially open structure.
• a slip concentration that is too high may make complete removal of excess slip difficult from the foam with the result of blocked pores.
• too low a slip concentration may result in incomplete coating of the foam carrier.
• the foam carrier preferably comprises a reticulated foam which will typically have a pore density of from 30 to 80 pores per inch, preferably 40 to 70 pores per inch, more preferably 45 to 60 pores per inch.
• the foam carrier is formed from a material that can be burnt off to leave a substantially unsupported ceramic/glass foam.
• the foam carrier is preferably formed from a resilient and flexible material such as a polymer or a rubber, although paper and cardboard materials may also be used for some applications.
• the preferred foam carrier is based on polyurethane and may be obtained from Commercial Foam Ltd. Such a material, which is resilient and flexible, may be compressed following the application of the slip. In this manner, excess slip is removed and once the compression force is removed the foam reverts to its original form. Compression may be achieved by passing the foam between rollers for example. Hydrophilic polymers, may also be preferably used for the foam carrier.
• a reticulated foam carrier of polyurethane is immersed in a bath of the slip.
• the foam carrier is removed from the bath and then compressed to remove the excess slip.
• the ceramic/glass impregnated carrier foam is heated to burn off the polyurethane, thus leaving a substantially unsupported reticulated ceramic/glass foam.
• substantially all of the glass particulate has a particle size of less than 100 ⁇ m, more preferably less than 85 ⁇ m.
• substantially all of the ceramic particulate or the ceramic-glass particulate has a particle size of less than 100 ⁇ m, more preferably less than 85 ⁇ m.
• the ceramic particulate may be selected from one or both of hydroxyapatite and apatite, including substituted-hydroxyapatite and substituted-apatite .
• the ceramic particulate may preferably be either a spray dried and/or calcined powder, or it may be directly obtained from the as-precipitated filter cake.
• a preferred hydroxyapatite is commercially available from Plasma Biotal Ltd.
• the biocompatible glass for the glass particulate may be produced by conventional glass melting techniques.
• the glass is preferably melted in a platinum crucible at a temperature of from 1000 to 1300°C and preferably then quenched to prevent devitrification.
• the glass is typically then ground for up to 24 hours in a porcelain ball mill to produce a fine powder.
• a suitable ball is available from Pascal Ltd.
• the biocompatible glass is preferably based on an oxide composition comprising one or more of CaO, P 2 0 5 , MgO, Na 2 0 and A1 2 0 3 and will typically be contained in the slip in an amount of up to 10 wt.% based on the total weight of the particulate, preferably up to 5 wt.%, more preferably from 1 to 3 wt.%.
• Suitable biocompatible glasses for use in the present invention are, for example, one or more of: a two oxide glass, such as CaO-P 2 0 5 ; a three oxide glass, such as CaO-Na 2 0-P 2 0 5 , CaO-MgO-P 2 0 5 or CaO-CaF 2 - P 2 0 5 glass; and a four oxide, such as CaO-Na 2 0-Al 2 0 3 - P 2 0 5 and a CaO-MgO-CaF 2 -P 2 0 5 .
• Other components may be incorporated into the biocompatible glass based upon CaO and P 2 0 5 , provided that the metals of the oxide used in the formation thereof are compatible with the body.
• a particularly preferred biocompatible glass for use in the present invention is a two oxide CaO-P 2 0 5 glass.
• the mole ratio of CaO to P 2 0 5 in these glasses may vary within wide limits but preferably is from 20:80 to 80:20 mol %.
• the glass having a mole ratio of CaO:P 2 0 5 of about 50:50 is particularly preferred. If CaF 2 , or any other compound containing calcium, is used as the source of F " ions (see below) , the amount of Ca in this compound is added to the amount of CaO when determining the above ratio. Thus by using such a compound the amount of CaO in the glass may be reduced if appropriate.
• liquid carrier examples include water, preferably double distilled water, alcohols, such as methanol and propan-2-ol, and hydrocarbons, such as trichloroethane.
• the slip may suitably be prepared by combining the constituents into a homogenous mixture.
• the glass constituent may first be ground dry for up to 24 hours.
• Particulate hydroxyapatite may then be added to the particulate glass in an amount to give a glass addition 'of, for example, up to 5 wt.%.
• a suspending medium is also added in the form of a solvent.
• the solvent is preferably substantially water free and methanol may advantageously be used as the solvent if the glass is degradeable.
• the solvent and glass/ceramic mixture is then mixed and optionally ground for up to 24 hours.
• the slip is then dried for example by gentle heating at a temperature of up to 80°C for up to 24 hours.
• the friable powder When dry, the friable powder may be passed through sieves to give a fine free flowing powder of preferably less than 85 ⁇ m that may be pressed.
• the liquid carrier for example water, may then be added to the mixed powder to form a slip or slurry, together optionally with the deflocculant.
• the ceramic particulate/glass particulate will generally be present in the liquid carrier in an amount of from 50 to 80 wt.%, more preferably 55 to 75 wt.%, still more preferably 60 to 70 wt.%, still more preferably approximately 65 wt.%.
• the slip may further comprise a source of fluoride ions.
• the source of fluoride ions preferably comprises an alkali metal or alkaline earth metal fluoride and suitable examples include one or more of CaF 2 , NaF and MgF 2 .
• the source of fluoride ions may be incorporated in the biocompatible glass or, alternatively, may be provided as a separate component in the slip.
• the slip-covered foam carrier is preferably dried prior to the burn-out step. Allowing the liquid carrier to evaporate from the ceramic slip coating is advantageous because excess liquid during the burn-out step can affect the properties of the final ceramic/glass foam and may result in cracking during subsequent heat-treatment.
• the slip-covered foam carrier may advantageously be heated to facilitate evaporation of the liquid carrier.
• burn-out temperature will depend upon the nature of the foam carrier. Burn-out should preferably be carried out slowly in order to avoid creation of pressures due to decomposition of the foam carrier and evaporation of any residual moisture. Sufficient amounts of oxygen or air should preferably be supplied so that substantially complete burn-out of the foam carrier can occur. Burn-out is therefore advantageously carried out in a ventilated furnace. Heating of the ceramic slip is carried our at a rate and temperature sufficient to substantially burn-out the precursor foam carrier.
• the resulting substantially unsupported ceramic/glass foam may be sintered under conditions to achieve the desired phases and microstructure.
• the unsupported ceramic/glass foam may be coated itself with slip to form a second coating thereon.
• the slip may have the same composition as the initial slip or may have a different composition.
• the slip-coated ceramic/glass foam is then preferably allowed to dry. This process may be repeated one or more times to build up a layered structure prior to sintering. Further slip coatings may be applied to a "green" unsupported ceramic/glass foam or to a sintered ceramic/glass foam.
• sintering temperature and sintering atmosphere will depend upon the nature of the ceramic/glass particulate and also the desired properties of the material, for example microstructure and chemistry. It will be appreciated that the sintering temperature and atmosphere must be chosen carefully to avoid decomposition of the ceramic material.
• the final phase composition of the sintered material will depend upon the starting materials and the sintering temperature.
• the glass-reinforced ceramic foam will typically comprise one or more of the following phases: hydroxyapatite, ⁇ -TCP and ⁇ -TCP (tricalcium phosphate) .
• the substantially dry ceramic/glass coated foam carrier may undergo a stepped heat- treatment for foam burn-out and densification by sintering.
• the optimum parameters for the burn-out step will depend on the foam being used.
• coated foams such as polyurethane, are typically heated at a rate of from 1 to 5 °Cmin" 1 r preferably 1 to 3°Cmin _1 , and held at a burn-out temperature of from 550 to 650°C, preferably approximately 600°C for up to approximately 1 to 2 hours.
• air may be passed through the furnace to ensure substantial removal of the foam.
• the unsupported ceramic/glass foam may be heated directly from the burn-out temperature, at a rate typically up to approximately 5°Cmin _1 , to a sintering temperature appropriate for the ceramic/glass powders, typically from 1100 to 1400°C, more typically 1200 to 1350°C, still more typically approximately 1250°C.
• the unsupported ceramic/glass may be cooled to room temperature and then sintered. On cooling, the sintered bodies are removed from the furnace and may be machined into the desired geometry.
• the resulting glass-reinforced ceramic foam material may be provided in the form of, for example, blocks, cylinders and granules.
• the sintered ceramic-glass foam produced according to the method of present invention typically has a compression strength of from 0.01 to 0.09 MPA, preferably from 0.02 to 0.09 MPA, more preferably from 0.04 to 0.09 MPA.
• the foamed ceramic-glass material produced by the method according to the present invention may be used as a synthetic bone material, including dental materials, for example for use in bone reconstruction and augmentation, implants, and compaction graft-type fillers and for making hydroxyapatite-polymer composites .
• the present invention also provides a glass- reinforced ceramic foam material for use in biomedical applications and comprising hydroxyapatite and a biocompatible glass and optionally a source of fluoride ions.
• the present invention also provides a glass- reinforced ceramic foam material whenever produced by a method as herein described.
• the present invention also provides a synthetic bone material which comprises a glass-reinforced ceramic foam material as herein described.
• the present invention also provides a composition which comprises a glass-reinforced ceramic foam material or a synthetic bone material as herein described, together with a pharmaceutically acceptable diluent or carrier.
• the present invention also provides a bone implant, filler, cement, tissue engineering scaffold, synthetic bone graft or drug-delivery device which comprises a glass-reinforced ceramic foam material, a synthetic bone material or a composition as herein described.
• the present invention also provides a glass- reinforced ceramic foam material, a synthetic bone material or a composition as herein described for use in a method of treatment of the human or animal body by surgery or therapy.
• Figure 1 shows a comparison of the compression strength between two sintered glass-reinforced ceramic foam materials according to the present invention.
• the material comprises hydroxyapatite and approximately 2 wt.% of a CaO-MgO-P 2 0 5 glass, based on the total weight of the hydroxyapatite and the glass.
• the precursor foam carrier had a pore density of 45 pores per inch.
• the first material was formed by applying a single coating of slip onto the precursor foam carrier, while the second material was formed by applying a second coating of slip.
• Figure 2 shows the same comparison as Figure 1 but for a foam carrier having a pore density of 60 pores per inch.
• Figure 3 shows a comparison of the compression strength between two sintered glass-reinforced ceramic foam materials according to the present invention.
• the material comprises hydroxyapatite and approximately 2 wt.% of a Ca0-Mg0-CaF 2 -P 2 0 5 glass, based on the total weight of the hydroxyapatite and the glass.
• the precursor foam carrier had a pore density of 45 pores per inch.
• the first material was formed by applying a single coating of slip onto the precursor foam carrier, while the second material was formed by applying a second coating of slip.
• Figure 4 shows the apparent density for a range of a sintered glass-reinforced ceramic foam materials according to the present invention comprising hydroxyapatite and approximately 2 wt.% (based on the total weight of the hydroxyapatite and the glass) of one of the following glasses: CaO-MgO-P 2 0 5 , CaO-MgO-CaF 2 -
• the materials were formed by applying a single coating of slip onto the precursor foam carrier.
• Precursor foam carriers with pore densities of 45 and 60 pores per inch were used.
• Figure 5 shows the apparent density for the same materials featured in Figure 4. In this case, however, a second coating of slip was applied to the precursor foam carriers.
• Figure 6 is a SEM micrograph of a sintered glass- reinforced ceramic foam material according to the present invention (magnification x 19.4, one coating applied) .
• the material comprises hydroxyapatite and approximately 2 wt.% of a CaO- MgO-P 2 0 5 glass, based on the total weight of the hydroxyapatite and the glass.
• the precursor foam carrier had a pore density of 45 pores per inch.
• Figure 7 is a SEM micrograph of a sintered glass- reinforced ceramic foam material according to the present invention (magnification x 19.8, one coating applied) .
• The. material comprises hydroxyapatite and approximately 2 wt.% of a CaO- Na 2 0-P 2 0 5 . glass, based on. the total weight of the hydroxyapatite and the glass.
• the precursor foam carrier had a pore density of 60 pores per inch.
• Figures 8 (a) and (b) shows a comparison of the compression strength between a variety of sintered glass-reinforced ceramic foam materials according to the present invention.
• a comparison with pure hydroxyapatite is provided.
• a comparison is also provided for single and double coatings.
• the materials comprise hydroxyapatite and approximately 2 wt.% of the glass materials recited below in Table 1 based on the total weight of the hydroxyapatite and the glass.
• the precursor foam carrier had a pore density of 45 pores per inch.
• the glass-reinforced ceramic foam material according to the present invention has enhanced mechanical and biological properties and a highly controlled reticulated foam structure.
• the material may be used for space filling and in tissue regeneration. It may also be used to act as a carrier for both inorganic and organic species, due to the extremely high surface area and the interconnected porosity.
• the glass-reinforced ceramic foam material may be used to carry agents such as bone morphogenetic proteins (BMPs) to enhance fracture healing and agents to control infection and suppress destructive aspects of the host response.
• BMPs bone morphogenetic proteins
• the ceramic-foam material is glass- reinforced it can sustain higher loads (compared with non-glass-reinforced materials) and will therefore be integrated more quickly into surrounding tissue. This has particular implications for patients, as it will mean shortened recovery times and enhanced regeneration of lost hard tissue.

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• 2000
  • 2000-06-07 GB GBGB0013870.1A patent/GB0013870D0/en not_active Ceased
• 2001
  • 2001-06-07 AU AU2001262533A patent/AU2001262533A1/en not_active Abandoned
  • 2001-06-07 EP EP01936664A patent/EP1335888A1/de active Pending
  • 2001-06-07 WO PCT/GB2001/002507 patent/WO2001094274A1/en active Application Filing

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